Track shoe

ABSTRACT

A track shoe for a crawler track has a hollow body with top and bottom sections and perimeter side walls defining a void therebetween. A supporting pillar is located in the void and extends between the top and bottom sections. The pillar is located in the main loadbearing region of the shoe and bears most of the load on the shoe. This enables the thickness of the side walls to be minimized. The shoe can be manufactured more efficiently by complementing foundry methods.

THIS INVENTION relates to a track shoe for a crawler track. Inparticular, the invention is directed to a crawler track shoe for anelectric mining shovel, although the invention is not limited to thatparticular use.

BACKGROUND ART

Some items of large mining machinery, such as excavators and shovels,are fitted with crawler tracks for locomotion. The individual links ofthe crawler tracks are known as “shoes”. These shoes are linked togetherby pins to form an endless articulated track, each track being mountedon support rollers with sprockets at either end.

The track shoes must support a heavy weight, and are subject to highpressures. Further, the tracks are often required to operate in harshconditions, such as stony or rock-strewn ground. Hence, the track shoesmust be of sufficient size and strength to withstand such conditions.

Track shoes are normally made of cast steel or other ferrous material,and then subjected to further foundry processing, such as heattreatment, to increase strength.

To cope with the high loads and harsh operating conditions, track shoeshave been made bigger, with some shoes being over 2 meters wide.However, increasing the size of the shoes increases their cost andweight. The heavier shoes are harder to handle, and increase the load tobe moved.

It is known to use hollow shoes having a plurality of internal walls orribs for strengthening. However, such internally-ribbed hollow shoes arerelatively expensive and difficult to manufacture, and have limitedapplication.

It is an object of this invention to provide an improved crawler trackshoe which overcomes or ameliorates the abovedescribed disadvantages, orwhich at least provides the consumer with a useful choice.

SUMMARY OF THE INVENTION

In one broad form, the invention provides a track shoe for a crawlertrack, the track shoe having a hollow body with top and bottom portionsseparated by a void, characterised in that the shoe includes asupporting portion located in the void and extending between the top andbottom portions.

The term “hollow body” as used in this specification is intended to meanthat the body has one or more voids or cavities therein.

Typically, the supporting portion is a pillar-like portion which isintegrally cast with the body. The pillar-like portion is advantageouslylocated under the main loadbearing region, and is surrounded by the voidwithin the hollow body.

The pillar-like portion bears most of the load carried by the shoe,thereby enabling the thickness of the shoe walls to be minimised. Thethickness may be optimised by computer-aided design using finite elementanalysis.

In order that the invention may be more fully understood and put intopractice, a preferred embodiment will now be described with reference tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a track shoe according to one embodimentof this invention,

FIG. 2 is a sectional perspective view of the track shoe of FIG. 1,

FIG. 3 is a part-sectional plan view of the track shoe of FIG. 1,

FIG. 4 is a part-sectional elevation of the track shoe of FIG. 1,

FIG. 5 is an end elevation of the track shoe of FIG. 1,

FIG. 6 is a sectional elevation along A—A of FIG. 3,

FIG. 7 is a sectional elevation along B—B of FIG. 3,

FIG. 8 is a sectional elevation along C—C of FIG. 3,

FIG. 9 is a sectional elevation along D—D of FIG. 3, and

FIG. 10 is a sectional elevation along E—E of FIG. 3.

DESCRIPTION OF PREFERRED EMBODIMENT

As shown in the drawings, a crawler track shoe 10 comprises a generallyflat body 11 having linking lugs 12 on either side thereof. In use,adjacent track shoes are pivotally linked by pins passing throughregistered pin holes in overlapping lugs 12. In this manner, the shoes10 can be chain-linked to form an endless track.

As shown more clearly in the sectional diagrams of FIGS. 2, 6-10, thebody 11 is a hollow body having top and bottom portions 11A, 11Bseparated by a void. The top and bottom sections 11A, 11B are generallyplanar. The top section 11A typically has boss-like protrusions 11Cwhich are engaged by the crawler sprockets.

The track shoe 10 has a support or reinforcing portion 14 extendingbetween the top and bottom portions 11A, 11B and formed integrallytherewith. The supporting portion 14 is preferably in the form of ashort, thick pillar-like stock and, for ease of description, the supportportion 14 shall be referred to as a “pillar”.

The pillar 14 of the illustrated embodiment is generally circular inshape, but may be of any other suitable cross section, such as oval,square or other polygon.

The pillar 14 is typically made of the same ferrous material as the body11, and is cast integrally with the body 11. Typically, the body andpillar are made of cast steel, which is subjected to heat treatment foradded strength.

The pillar 14 is advantageously located under the main load bearingregion (namely, the middle portion) of the track shoe 10. In theillustrated embodiment, the supporting portion comprises a single pillar14 surrounded by the void of the hollow track shoe. However, thesupporting portion may be in the form of a plurality of pillars locatedin the main load bearing region of the track shoe.

The illustrated embodiment has a number of advantages, including

By locating the pillar(s) 14 directly under the main loadbearing region,it bears most of the load. The remaining walls can therefore be madethinner, resulting in strength-to-weight benefits.

The use of the central pillar under the roller path (the mainloadbearing region) significantly boosts the strength of the track shoe,and enables the track shoe to be manufactured more efficiently by knownfoundry methods.

The illustrated track shoe design allows bending loads to be transferredmore smoothly from section to section, which reduces stressconcentrations and complements foundry methods.

By locating the pillar in the main loadbearing region, the number ofcore pieces in the track shoe is reduced, thereby reducing the cost ofmanufacture.

The foregoing describes only one embodiment of the invention, andmodifications which are obvious to those skilled in the art may be madethereto without departing from the scope of the invention as defined inthe following claims.

What is claimed is:
 1. A crawler track shoe adapted for excavationmachinery, the shoe comprising a cast unipartite hollow body ofgenerally elongate form having a load bearing top wall and a groundengaging bottom wall, the top and bottom walls being separated by aninternal void, perimeter side walls extending between the top and bottomwalls and at least partially surrounding the void laterally, offsetconnection lugs extending outwardly from respective opposite sides ofthe body to permit like shoes to be joined by pins inserted throughaligned apertures in overlapping lugs to form a crawler track, and atleast one integrally formed pillar-like supporting portion located inthe void and extending between the top and bottom walls, the top wallhaving a roller path on the upper side thereof defining the main loadbearing area of the top wall, the supporting portion being completelysurrounded on all sides by the void and located directly under theroller path of the top wall so as to bear a load applied to the rollerpath of the shoe and thereby permit the thickness of the side walls ofthe hollow body to be reduced.
 2. The track shoe of claim 1 is made ofcast steel.
 3. The track shoe of claim 1 wherein the supporting portioncomprises a single pillar-like structure.
 4. The track shoe of claim 1wherein the supporting portion comprises a plurality of pillar-likestructures.
 5. The track shoe of claim 1 is further linked with adjacenttrack shoes in a manner so as to form an endless track.